Can we predict who will develop bipolar disorder (BD)?

This is the aim of a study instigated four years ago by Professor Phillip Mitchell, head of the school of psychiatry at the University of NSW.

The prospective longitudinal Bipolar Kids and Sibs Study has enrolled 150 children and young adults aged between 12 and 30 who are at risk of (BD) because they have a first degree relative with the disorder. Ten per cent of these individuals can be expected to go on to develop BD.

Presenting at the 14th International Mental Health Conference on the Gold Coast last month, Professor Mitchell revealed some intriguing findings from the four-year analysis of the study.

A third of the at-risk group had affective disorders, mainly depression, compared with 12% in the control group and 44% in the BD group.

The at-risk group also had high rates of anxiety and behavioural disorders, around twofold higher than controls, with the BD group around eightfold higher.

“What’s striking is you can see the at-risk group are in the middle between the controls and BD group,” Professor Mitchell says.

“They are intermediate. What it’s indicating is they are starting to show the pattern of people with BD.”

What is even more striking is the time course of age of onset for anxiety and affective disorders.

It shows that onset occurs earliest in the BD group, with the line for the at-risk group midway between the BD and controls.

Professor Mitchell says the data matches Canadian and US studies and the three research groups are starting to develop a theoretical model of how BD may present.

“The kid is well and then they start to present with non-mood disorders, like anxiety and behavioural problems before they go on to develop clear depression and mania,” he says.

But it’s unclear what this means.

“Does it mean it’s a risk factor, so having anxiety just makes it more likely? Or, another way of looking at it that’s really interesting is, is it in fact how the tendency to the illness is presenting?”

Professor Mitchell says it’s too early to distinguish between the two possibilities, but treating anxiety could reduce the risk of a child developing BD.

“If you’ve got a kid who’s in a family that’s got a risk of BD and they are presenting with clear-cut anxiety, then I think there’s an imperative to make sure that anxiety is actively treated,” he says.

“I think this will change how we look at illness in years to come.”

This article first appeared on Medical Observer on 17 September, 2013.